Drilling bottom hole assemblies (BHA's) can include a drilling motor which provides for rotation of a drill bit at an end of a drill string. However, if a drilling BHA includes a positive displacement Moineau-type drilling motor, a rotor of the drilling motor may have an articulating, planetary and/or epicyclic motion, which is preferably transformed into rotary motion of the drill bit. Furthermore, if a bent housing is used in the drilling BHA, rotation about one centerline of the BHA is preferably transformed into rotation about another centerline which is not aligned with the first centerline.
Therefore, it will be appreciated that improvements are continually needed in the art of constructing constant velocity connections for transmitting rotation and torque between a drilling motor and a drill bit.